Letter to the Editors

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The explicit purpose of this paper is to exclude the role of chrysotile in the mesothelioma epi­demics among workers of the former San Vittore mine (Amiantifera di Balangero) and inhabitants in the Balangero area. In search of other causes, gross mistakes have been made by Ilgren et al. The paper is full of statements that have no substance and lack support of evidence. We will comment the most important ones.

The mine is one of the few chrysotile mines where pure chrysotile is obtained, with the only exception of balangeroite – a local, low persistency, non-amphibole mineral fiber – that occurs in very minor amounts [2,3], in the order of 0.2 – 0.5% of total extracted chrysotile [4].

Tremolite outcrops are occasionally present in some locations of the Piedmont Region area, but not close to the actual mine location. The outcroppings of tremolite reported by Ilgren et al. in the Susa Valley are separated from the Balangero area by a line of mountains exceeding 2000 m. The other outcrops mentioned by Ilgren et al in Trana or Val Macra are at even greater distance and separation from Balangero, as everyone can easily check on a map. In any case, tremolite was not reported as a contaminant of Balangero chrysotile. Similar conclusions (misreported by Ilgren et al) were presented by Pira et al, ref 15 in Ilgren et al [3]: “Examination of several samples of chrysotile from the mine ruled out the presence of contamination with fibrous amphiboles at detect­able concentrations”.

There is no trace in the whole body of the Western Alps of natural sources of the other amphi­boles, e.g. crocidolite and amosite, contrary to statements by Ilgren et al., for the following reasons. Amosite, the asbestiform variety of grunerite, is a characteristic mineral of metamorphosed iron-rich siliceous sediments [5]. Crocidolite, the asbestiform variety of riebeckite, is typical of the “banded ironstones” of South Africa or the equivalent “banded iron formations” of Western Australia [5]. Both asbestiform minerals are naturally unknown in the Western Alps, because they were formed in pecu­liar geologic environments lacking in Italy. This is especially true for the Balangero mine that occurs in a serpentinised mantle peridotite, i.e. in a lithology whose bulk chemical composition is far from those suited to grow amosite or crocidolite.

Ilgren et al. appear unfamiliar not only with the geology of the area, but also with the roads, as no one familiar with the roads could ever imagine workers commuting from Balangero to Casale Monferrato. Ilgren indicates as a matter of fact that: Balangero was not too far from Casale Monferrato, that the Balangero mine interrupted activities in winter and that an unspecified number of Balangero miners commuted for ‘moonlight work’ to Casale Monferrato. None of these statements is supported by any evidence and all are unlikely or false. As for the distance: the shortest travelling distance from Balangero to Casale Monferrato is 97 km: nowadays travelling by car from Balangero to Casale Monferrato takes an estimated time of 1 h and 37 min (http://www.viamichelin.it) and a cost of 14.5 € for fuel and tolls alone. Travelling by public transport nowadays takes over 3 hours, one way. As for the mine activity in winter: the mine area ranges from 600 to 800 m above the see level (http://it.wikipedia.org/wiki/Amiantifera_di_Balangero); except for rare heavy snow falls, the mine was active all the year round, as clearly documented by the reports, the documents of the court trial that took place in Ciriè [6] and the dates of asbestos sampling campaigns. As for the evidence: the Mesothelioma Registry of Region Piedmont investigates occupational and residential history of mesothelioma cases and we have followed-up the cohort of Eternit workers of Casale Monferrato; neither source got any indications of commuting as suggested by Ilgren et al and moreover we did not record Eternit workers coming from the Balangero area. None of the reported cases of MM from the Balangero mine ever worked in Casale Monferrato Eternit plant.

Ilgren et al suggest that large amounts of crocidolite were used in Balangero, with repeated state­ments not supported by sound references. 1) Ilgren quotes ref 11 in [1] as: ‘…Crocidolite and amosite were also transferred to Balangero in Jute bags’.


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